• A Dynamic Approach to Grazing Management Terminology

      Scarnecchia, D. L.; Kothmann, M. M. (Society for Range Management, 1982-03-01)
      Expressions such as stocking density, stocking rate, grazing pressure, herbage allowance, grazing intensity and stocking pressure have long been used to describe animal-pasture systems. These expressions describe relationships among the basic variables of animal demand, forage quantity, pasture area, and grazing duration. Our objective was to develop a dynamic, mathematical framework of expressions summarizing all of the meaningful relationships among these variables. The resulting expressions have dimensional validity, and are useful in describing dynamic animal-pasture systems. The expressions should also prove useful in future efforts to model these systems.
    • Brownseed Paspalum Response to Season of Burning

      Scifres, C. J.; Duncan, K. W. (Society for Range Management, 1982-03-01)
      Season of burning as related to plant phenology, maximum temperatures achieved, and soil water content rather than duration of heat exposure (5, 15 or 30 seconds) apparently regulated fire-induced mortality of brownseed paspalum. Burning or top removal by clipping to ground line during the summer caused greatest mortality of brownseed paspalum and reduced herbage volume of surviving plants, whereas burning in early or mid-spring resulted in favorable growth responses. Fall burning was less damaging than summer burning but caused greater mortality of brownseed paspalum than did burning in the spring. Regrowth of brownseed paspalum after spring burning was equivalent to that following top removal by clipping during the same season. However, responses to summer or fall burning indicated that heat-induced damage (and/or perhaps subsequent winter kill following fall burns) occurred in addition to the effects of simple top removal.
    • Cattle Diets in the Blue Mountains of Oregon II. Forests

      Holechek, J. L.; Vavra, M.; Skovlin, J.; Krueger, W. C. (Society for Range Management, 1982-03-01)
      Esophageally fistulated cows were used on forested range in northeastern Oregon to collect diet samples which were then analyzed by the microhistological technique. Grasses, forbs, and shrubs averaged 61, 16, and 23% of the diet, respectively. Composition of diets differed among years and with seasonal advance. Idaho fescue and elk sedge were the most important forage species consumed. Forbs were used heavily in the early part of the grazing season before maturation. Browse comprised as much as 47% of the diet when green grass was unavailable. Cattle were opportunistic grazers and did not limit their selection to grass species. On forested ranges cattle diets varied among grazing periods within each year as well as among years.
    • Changes in the Yield of Forage Following the Use of Herbicides to Control Aspen Poplar

      Bowes, G. G. (Society for Range Management, 1982-03-01)
      Yields of forage were measured 3 to 5 years after the use of 2,4-D, 2,4-D + 2,4,5-T, and picloram + 2,4-D applied at brush control rates. The yield of bromegrass and alfalfa on the herbicide treated areas was either reduced or remained unchanged. This occurred because alfalfa can not tolerate the high herbicide rates required for brush control. On an area which never received a herbicide treatment, alfalfa was unable to compete with invading aspen poplar and prickly rose. Ranchers should use herbicides to prevent secondary succession from grasslands to the aspen poplar vegetation type which has a low amount of forage available for cattle. Arguments are presented for including alfalfa in a seeding program when a mixture of 2,4-D + picloram is used for brush control but not when a mixture of 2,4-D + 2,4,5-T is used.
    • Concentration of Monoterpenoids in the Rumen Ingesta of Wild Mule Deer

      Cluff, L. K.; Welch, B. L.; Pederson, J. C.; Brotherson, J. D. (Society for Range Management, 1982-03-01)
      Forage from a sagebrush-dominated winter range and rumen ingesta from mule deer wintering on this range were analyzed for monoterpenoids. The average monoterpenoid level of the rumen ingesta was 0.3%, compared with an average of 1.64% expected from the proportion of monoterpenoid-containing plants in the diet. This 80% reduction between the monoterpenoid level from the rumen compared to the level expected from the ingested forage was highly significant (p<.01). The exact method in which the monoterpenoids are lost from the ingesta was not determined, but evidence from other studies suggests that monoterpenoids may be lost from ingested forage as early as the mastication process. The amount of monoterpenoids found in the rumen ingesta at the time of sampling does not appear to be high enough to interfere with microbial activity. This loss of monoterpenoids may explain the conflict between in vitro evidence that big sagebrush monoterpenoids inhibit rumen microorganisms and digestive trials which show that big sagebrush is a highly digestible winter forage.
    • Cow-Calf Response to Stocking Rates, Grazing Systems, and Winter Supplementation at the Texas Experimental Ranch

      Heitschmidt, R. K.; Kothmann, M. M.; Rawlins, W. J. (Society for Range Management, 1982-03-01)
      Cow-calf performance from 1960 through 1978 was contrasted between three grazing treatments at the Texas Experimental Ranch. Grazing treatments were yearlong continuous stocked at annual rates averaging 5.1 and 7.6 ha/cow and a 4-pasture, 3-herd deferred rotation system stocked at an annual rate averaging 7.2 ha/cow. Averaged across three weighing periods, cows in the deferred rotation treatment averaged 447 kg while weight of cows in the heavily and moderately stocked continuous treatments averaged 427 and 438 kg, respectively. Calf weaning weights averaged 204, 212, and 217 kg for the heavy continuous, moderate continuous, and Merrill rotation treatments, respectively. Production-/cow averaged 182, 189, and 202 kg while production/ha averaged 35.9, 25.2, and 27.8 kg, respectively, for the heavy continuous, moderate continuous, and deferred rotation treatments. Cows fed winter supplement were significantly heavier in early spring and summer than nonsupplemented cows with no significant differences in weights by late summer. Supplemented cows weaned calves averaging 214 kg as compared to 208 kg for calves weaned from nonsupplemented cows. Winter supplementation significantly increased production in the heavily stocked treatment but not in either of the moderately stocked treatments. Numerous statistically significant interactions accompanied the significant main effects, and the biological significance of each was examined.
    • Destructive and Potentially Destructive Insects of Snakeweed in Western Texas and Eastern New Mexico and a Dioristic Model of Their Biotic Interactions

      Wangberg, J. K. (Society for Range Management, 1982-03-01)
      The relationships of the principal destructive and potentially destructive insects associated with Xanthocephalum microcephalum (DC) Shinners (threadleaf snakeweed) and Xanthocephalum sarothrae (Pursh) Shinners (broom snakeweed) have been identified and depicted with a dioristic model. Every region of the host plant is utilized by insects in one or more of the following feeding categories: defoliators, fluid feeders, borers, and gall-formers. Roots, stems, leaves, flowers, and fruit each have their own complement of insect associates. A system analysis reveals a complex picture of insect-host plant interactions as well as potential insect-insect interactions. The roles that these insects play in the natural biological control of threadleaf and broom snakeweed are poorly understood but the general information portrayed in the model of their interactions will help future workers to determine the most productive avenues of research.
    • Disturbance and Revegetation of Sonoran Desert Vegetation in an Arizona Powerline Corridor

      Hessing, M. B.; Johnson, C. D. (Society for Range Management, 1982-03-01)
      Rates and patterns of revegetation were studied during and after construction of the 500 kV Navajo Project Southern Transmission Line at two sites in the Arizona Sonoran Desert from 1972 through 1977. Herbs were reduced temporarily during the construction phase of the study. Perennial herbs did not return in the 5-year post-construction period. Annual herbs invaded immediately after disturbance. In one case annual herb density and diversity was higher after disturbance due to removal of larger woody plants. The tree and shrub community exhibited dynamic changes in cover, diversity, and richness, presumably in response to the climate. However, colonization by new species was not observed during the 5 years of study. Colonization by previously existing species seemed to be limited to Ambrosia deltoidea, probably due to its ability to reproduce vegetatively and to annual herbs. Annuals which were also on two control plots were probably a colonizing sere of plants.
    • Effect of Seasonal Herbage Allowance on Bolus Weight of Cattle

      Stuth, J. W.; Angell, R. F. (Society for Range Management, 1982-03-01)
      Technology has recently made it possible to count forage boli consumed daily in ruminants. This technique can presently be used to measure grazing time and rates of nutrient intake. However, to determine total daily intake, the influence of inherent variations in bolus weight and associated forage conditions must be known. An attempt was made to determine if degree of uniformity in forage boli weights were statistically nonsignificant to be counted and used as a measure of daily dry matter intake of an animal. Herbage allowances varying from 15.4 to 3.4 kg DM/100 kg BW/day did not have a significant effect on bolus weights in mature cows grazing bahiagrass pastures during mid-summer and early winter (P≤0.05). Cow size and season of the year also had no significant effect on bolus weight. Bolus weight of the cows averaged 4.4 +/- 0.1 g across seasons and cows.
    • Effects of Precipitation Variance on Annual Growth of 14 Species of Browse Shrubs In Southeastern Oregon

      Kindschy, R. R. (Society for Range Management, 1982-03-01)
      Growth response of 14 species of shrubs to precipitation occurring between September and June was measured during a 15-year period. Vegetative production was found to be significantly corrolated (p = 0.01) to precipitation. Regression analysis of 3,750 measurements of annual growth enabled the development of linear equations which may be used by habitat managers to forecast shrub browse production expressed as a percentage of normal production.
    • Factors Influencing Bitterweed Seed Germination

      Whisenant, S. G.; Ueckert, D. N. (Society for Range Management, 1982-03-01)
      Bitterweed seed germination exceeded 90% at constant temperatures between 20 degrees and 25 degrees C and more than 65% between 15 degrees and 30 degrees C in a controlled environment chamber. Seeds germinated equally well in light and dark conditions. Germination percentages of seeds in aqueous media with a pH range of 5 to 9 were significantly different, but the range of germination (91 to 97%) probably is not sufficient to affect distribution. However, a decrease in water availability significantly decreased bitterweed seed germination. Viability of bitterweed seed did not change significantly after 39 months dry storage at room temperature, but was significantly reduced at 47 months.
    • Factors Influencing Development of Cryptogamic Soil Crusts in Utah Deserts

      Anderson, D. C.; Harper, K. T.; Holmgren, R. C. (Society for Range Management, 1982-03-01)
      The relation of some physical and chemical soil characteristics to cryptogamic crust development was determined from sites in semidesert regions of southern Utah. The effects of grazing on cryptogamic crust development also was examined. Electrical conductivity, percentage silt, and soil phosphorus were found to be correlated with well-developed cryptogamic crusts. Both total cryptogamic cover and the number of cryptogamic species decreased under grazing pressure. The management of rangelands, especially in arid regions, would be strengthened by understanding the role of cryptogamic crusts and considering them in range management decisions.
    • Fluoride in Thermal Spring Water and in Plants of Nevada and Its Relationship to Fluorosis in Animals

      Kubota, J.; Naphan, E. A.; Oberly, G. H. (Society for Range Management, 1982-03-01)
      Fluoride concentrations in water from selected thermal springs and in plants were determined to evaluate their role as sources of F- for grazing animals in Nevada. The F- concentration in water varied with thermal spring sources and ranged from about 2 to 17 ppm. F- concentration in plants ranged from about 0.1 to over 220 ppm, depending upon species of plants and the soil on which the plants were grown. The F- concentration in plants from any given thermal spring location was not uniformly high, but together with F- concentration of the water, appears to contribute to possible cases of fluorosis in cattle. Although small area-wise the spring waters and the area they flow over are important to grazing animals, because they provide drinking water and have lush forage.
    • Foliage Mortality of Mountain Big Sagebrush in Southwestern Idaho during the Winter of 1976-77

      Hanson, C. L.; Johnson, C. W.; Wight, J. R. (Society for Range Management, 1982-03-01)
      Mountain big sagebrush (Artemisia tridentata subsp. vaseyana) in southwest Idaho suffered extensive overwinter foliage mortality during 1976-77 where the normally deep snow cover was lacking. Mortality was 75 to 100% in areas where snow usually covers dense stands of sagebrush; however, winterkill was slight in areas of usually shallow snow cover. Winter-induced physiologic drought caused by frozen soils, low soil water content, and above average air temperature was the apparent cause of sagebrush foliage mortality.
    • Food Resource Partitioning by Sympatric Ungulates on Great Basin Rangeland

      Hanley, T. A.; Hanley, K. A. (Society for Range Management, 1982-03-01)
      The usefulness of a conceptual framework for understanding food selection by ungulates, based on four morphological parameters (body size, type of digestive system, rumino-reticular volume to body weight ratio, and mouth size), was tested by applying discriminant analysis to 194 monthly diet determinations based on microhistological fecal analysis for five sympatric species of ungulates in northeastern California and northwestern Nevada. In each season, the group means were located in the hypothesized order along the axis described by the first discriminant function: feral horse, domestic cow, domestic sheep, pronghorn, mule deer. Horse and cow diets consisted primarily of grasses. Pronghorn and mule deer diets consisted primarily of browse. Sheep diets were intermediate. Four browses (Artemisia spp., Cercocarpus ledifolius, Purshia tridentata, and Juniperus occidentalis) were selected as the most useful species for discriminating between animal species. The data and analyses support the hypothesized food selection framework.
    • Grass Response Following Thinning of Broom Snakeweed

      McDaniel, K. C.; Pieper, R. D.; Donart, G. B. (Society for Range Management, 1982-03-01)
      Complete removal of broom snakeweed resulted in perennial grass production 833% of that on untreated rangeland after one growing season, and 712% and 300% the second and third year, on a pasture heavily grazed and in poor range condition. On a moderately grazed pasture in good range condition, grass standing crop increased 42% the first year, 81% the second, and 25% the third compared to untreated rangeland. Perennial grass production on the heavily grazed pasture was far below that on the moderately grazed pasture at the start of the study (40 vs 454 kg/ha). After 3 years, with complete broom snakeweed removal and no grazing, perennial grass production was comparable on the pastures once heavily and moderately grazed (1014 vs 939 kg/ha, respectively).
    • In Vitro Digestion—Sources of Within- and Between-Trial Variability

      Milchunas, D. G.; Baker, D. L. (Society for Range Management, 1982-03-01)
      Procedures for, and conditions during, inoculum collection and preparation, digestion, and residue recovery stages of the in vitro digestion technique were investigated to determine sources of within- and between-trial variability in digestion coefficients for forages of different chemical composition. Digestion coefficients differed significantly among inoculum preparation times of 1, 2, and 4 hours and for a decline in rumen fluid temperature to 29° in transport. These differences were not uniform across forage species and did not correlate with forage digestibility. Digestion coefficients differed significantly among inoculums prepared from fibrous deer rumen fluids that were strained only, strained and layered, and blended in a Waring blender and filtered through glass wool but did not differ between strained-layered and blended filtered inoculums of non-fibrous rumen fluid from a fistulated cow. Forage in vitro digestion in the absence of microbial activity (by solubility alone) indicated that forages having more soluble components were least affected by inoculums of different microbial activities, suggesting that between-trial differences be adjusted by a solubility, rather than a digestibility, factor. Inoculum nitrogen concentration did not correspond to between-trial differences in forage digestibility. Size of test tube, but not centrifugation versus filtration method of residue preparation, significantly affected digestion coefficients. However, because the standard large tube size cannot be centrifuged, the two methods of residue recovery would not be comparable unless the products of digestion were transferred from large tubes to centrifuge tubes. The end products of digestion must be stored under refrigeration if filtering proceeds for extended periods of time.
    • Increasing the Rate of Cattle Dung Decomposition by Nitrogen Fertilization

      Lussenhop, J.; Wicklow, D. T.; Kumar, R.; Lloyd, J. E. (Society for Range Management, 1982-03-01)
      Cattle dung on a Colorado range was subjected to 6 years of irrigation and nitrogen fertilization. Disappearance of the dung was determined by sampling particles >0.8 cm2. No particles remained in irrigated plots. Seventy-two percent less dung weight remained in nitrogen fertilized than in control plots. Nitrogen fertilization increased dung nitrogen concentration by 13%. We argue that fertilization increased weight loss by stimulating microbial growth.
    • Infiltration and Sediment Production on a Deep Hardland Range Site in North Central Texas

      Brock, J. H.; Blackburn, W. H.; Haas, R. H. (Society for Range Management, 1982-03-01)
      Greatest infiltration rate and lowest sediment production occurred in the honey mesquite canopy zone. Infiltration on shortgrass interspace areas was about one-half of the canopy zone rate. Terminal infiltration rates within the canopy zone and shortgrass interspace areas were affected little by brush control treatments. Infiltration rate improvement due to treatment occurred primarily in the midgrass interspace areas. Water-stable aggregates and the interaction of soil aggregate stability with the amount of bare ground were the dominant factors controlling infiltration. Sediment production on the shortgrass interspace was double that of the canopy zone or midgrass interspace areas. Low rate of sediment production on the midgrass interspace areas occurred on areas aerially sprayed or root plowed 3 years earlier. Sediment production was controlled primarily by an interaction of soil organic matter and amount of above-ground biomass or grass cover.